Thermal Conductivity and Microstructure of Cu-Coated Graphite Flake/Ti Alloy Composites Fabricated by Spark Plasma Sintering

Graphite flake (GF)-reinforced Ti6Al4V (TC4) matrix composites were fabricated by spark plasma sintering, and electroless copper (Cu) plating on the surface of the GFs was introduced to slow the interface reaction between the GFs and the TC4 and to improve the interface bonding. The effects of sintering temperature and coating thicknesses on the microstructure and thermal conductivity (TC) of the composites were investigated. The results showed that the introduction of the Cu coating can significantly reduce the thickness of the titanium carbide (TiC) layer generated by the interface reaction between the GFs and the TC4, increase the density of TiC layer, and thus increase the TC of the composite. When the sintering temperature was below 1150°C, the TC gradually increased from 185.03 W m −1 K −1 before Cu plating to 232.4 W m −1 K −1 with the increase of the Cu coating thickness and sintering temperature. When the temperature was further increased to 1200°C, the TC deteriorated due to the increase in the thickness of the TiC layer. The high TC makes the GF/TC4 composites suitable candidates for heat transfer materials used in offshore engineering.